1. Field of the Invention
The present invention generally relates to motor vehicle seats and, more specifically, the welding of parts together. The present invention more specifically relates to the welding of planar members by their edges on mobile slideway sections for vehicle seats.
2. Discussion of the Related Art
Motor vehicle seats are more and more often supported by slideways having a fixed section attached to the vehicle or to a seat support and having a mobile section capable of sliding with respect to the fixed section. The mobile section supports the seat framework and generally has the shape of an upside-down U. The seat framework is attached via vertical flanges welded to the upper surface (back of the U) of the mobile section. The weldings are performed by a laser welding technique where the beam is directed towards the junction between the parts to be welded.
FIG. 1 very schematically illustrates an example of conventional welding of a flange 40 on a U-shaped mobile section 3. The welding operations are performed laterally in two steps. A first run of a laser beam (symbolized by an arrow f1) performs welding 41 on one side of flange 40. A second run of the laser beam on the other side of the flange (symbolized by an arrow f2) performs a welding 42 on the other side. It is indeed necessary, to keep a proper resistance, to have a homogeneous welding over the entire area of contact between the materials forming the U-shaped section and flange 40.
The weldings are performed in a line due to the longitudinal shape of the sections. It can thus be seen that such a welding method requires two runs per flange 40 to be welded.
More recently, slideways for motor vehicle seats have been developed, on which two flanges (or the like members), parallel to each other in the longitudinal direction of the section, must be welded by their edges. A concern then is that the proximity of the flanges prevents any access to the internal side of the second flange to be welded.